Cogeneration system

BACKGROUND OF THE INVENTION

00011. Field of the Invention

0002The present invention relates to a cogeneration system in which both the electricity and waste heat generated from an engine are used, and, more particularly, to a cogeneration system in which waste heat generated from an engine is supplied to a heat exchanging zone of an indoor heat exchanger to achieve a heating operation.

00032. Description of the Related Art

0004In general, cogeneration systems are adapted to generate both electricity and heat from a single energy source.

0005Such a cogeneration system can recover heat of exhaust gas or waste heat of cooling water generated from an engine or turbine during an electricity generation operation, so that the cogeneration system can achieve an increase in energy efficiency of 70 to 80% over other systems. By virtue of such an advantage, the cogeneration system has recently been highlighted as an electricity and heat supply source for buildings. In particular, the cogeneration system exhibits highly-efficient energy utilization in that the recovered waste heat is mainly used to heat/cool a confined space and to heat water.

0006<figref idref="DRAWINGS">FIG. 1</figref> is a schematic configuration diagram illustrating a conventional cogeneration system used in a heating/cooling apparatus.

0007As shown in <figref idref="DRAWINGS">FIG. 1</figref>, the conventional cogeneration system includes a gas engine <b>1</b>, and a generator <b>3</b>, which is driven by a driving force outputted from the gas engine <b>1</b>, to generate electricity. The electricity generated from the generator <b>3</b> is used in a variety of devices including a cooling/heating unit <b>20</b>, illumination devices, and other electrical products.

0008In the cogeneration system, waste heat generated from the gas engine <b>1</b>, that is, heat of cooling water generated when the cooling water cools the gas engine <b>1</b>, and heat of exhaust gas generated from the gas engine <b>1</b>, is used during a heating operation of the cooling/heating unit <b>20</b>.

0009Here, the cooling/heating unit <b>20</b> is of a heat pump type so that the cooling/heating unit <b>20</b> not only can be used as a cooling unit, but also can be used as a heating unit in a state in which the refrigerant flow direction in the refrigerant cycle is reversed. As in a general heat pump type configuration, the cooling/heating unit <b>20</b> includes a compressor <b>21</b>, a four-way valve <b>23</b>, an outdoor heat exchanger <b>25</b>, an outdoor fan <b>26</b>, an expansion device <b>27</b>, and an indoor heat exchanger <b>29</b>.

0010In particular, an air pre-heating heat exchanger <b>30</b> is arranged at the side of the outdoor heat exchanger <b>25</b> to preheat air passing around the outdoor heat exchanger <b>25</b> during a heating operation of the cooling/heating unit <b>20</b>, using the waste heat of the gas engine <b>1</b>.

0011In order to supply the waste heat to the cooling/heating unit <b>20</b>, the cogeneration system also includes a cooling water heat exchanger <b>5</b> to recover the heat of the cooling water used to cool the gas engine <b>1</b>, and an exhaust gas heat exchanger <b>9</b> arranged at an exhaust conduit <b>7</b> to recover the heat of the exhaust gas.

0012The cooling water heat exchanger <b>5</b> and exhaust gas heat exchanger <b>9</b> are connected to the air pre-heating heat exchanger <b>30</b> of the cooling/heating unit <b>20</b> by a heat transfer line <b>11</b>, through which a heat transfer medium flows, so as to supply waste heat to the air pre-heating heat exchanger <b>30</b> during the heating operation of the cooling/heating unit <b>20</b>. Thus, the cogeneration system recovers engine heat and exhaust gas heat, pre-heats outdoor air through the air pre-heating heat exchanger <b>30</b>, using the recovered heat, and causes the pre-heated air to perform heat exchange with the outdoor heat exchanger <b>25</b>, thereby preventing a degradation in the heating performance of the cooling/heating unit <b>20</b>, which may occur when the temperature of the outdoor air is low.

0013When the cooling/heating unit <b>20</b> operates in a cooling mode, the flow path of the heat transfer medium is changed to communicate with a radiating line <b>13</b>, which is connected to the heat transfer line <b>11</b>, because it is unnecessary to supply waste heat. In this case, the waste heat is discharged to the atmosphere through a radiator <b>17</b>, which includes a heat exchanger <b>15</b> and a radiator fan <b>16</b>, or is supplied to and used in a water heater, a hot water supplier, or other systems.

0014In <figref idref="DRAWINGS">FIG. 1</figref>, reference character P designates pumps, each serving to force the heat transfer medium to flow through an associated portion of the heat transfer line <b>11</b>, and reference character V designates valves, each serving to switch the flow path of the heat transfer medium between the heat transfer line <b>11</b> and the radiating line <b>13</b>.

0015Although the waste heat generated from the gas engine <b>1</b> is used to pre-heat the outdoor heat exchanger <b>25</b> through the air pre-heating heat exchanger <b>30</b>, the conventional cogeneration system has a problem in that a degradation in energy efficiency occurs because the waste heat is not directly used to heat a confined space.

SUMMARY OF THE INVENTION

0016The present invention has been made in view of the above-mentioned problem, and it is an object of the invention to provide a cogeneration system in which waste heat generated from an engine is directly supplied to a fluid line connected to an indoor heat exchanger so that the waste heat is used to heat a confined space, thereby achieving an enhancement in heating efficiency.

0017Another object of the invention is to provide a cogeneration system in which waste heat generated from an engine is used to pre-heat a refrigerant passing through a suction line of a compressor, so that it is possible to prevent a degradation in heating performance during operation of a refrigerant cycle.

0018In accordance with one aspect, the present invention provides a cogeneration system comprising: an engine, which drives a generator to generate electricity; a cooling/heating unit, which comprises at least one compressor, a four-way valve, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger, to establish a heat pump type refrigerant cycle; and an exhaust heat consuming heating unit to supply heat of exhaust gas discharged from the engine to a heat exchanging zone of the indoor heat exchanger of the cooling/heating unit, and thus, to heat a confined space.

0019The exhaust heat consuming heating unit may comprise an exhaust gas heat exchanger arranged at an exhaust conduit, through which the exhaust gas passes, an indoor heater arranged at the heat exchanging zone of the indoor heat exchanger to perform heat exchange with indoor air, and a heating line, which connects the exhaust gas heat exchanger and the indoor heater to guide a heat transfer medium to flow between the exhaust gas heat exchanger and the indoor heater.

0020The exhaust heat consuming heating unit may further comprise an exhaust heat radiating unit to radiate heat recovered by the exhaust gas heat exchanger when it is unnecessary to supply heat to the indoor heater.

0021The exhaust heat radiating unit may comprise a radiating line branched from the heating line, a valve to bypass the heat transfer medium in the heating line through the radiating line, and a radiator arranged at the radiating line.

0022The indoor heater may be arranged in parallel with the indoor heat exchanger such that the indoor heater performs the heat exchange with the indoor air in accordance with an operation of an indoor fan.

0023The indoor heater may be arranged downstream from the indoor heat exchanger with respect to a flowing direction of the indoor air.

0024The cogeneration system may further comprise a refrigerant pre-heating unit to supply heat of cooling water used to cool the engine to a suction side of the compressor of the cooling/heating unit, and thus, to pre-heat a refrigerant passing through the suction side of the compressor.

0025The refrigerant pre-heating unit may comprise a cooling water line, through which the cooling water of the engine passes, and a cooling water heat exchanger to recover heat of the cooling water in the cooling water line, and to transfer the recovered heat to a refrigerant line connected to a suction section of the compressor.

0026The refrigerant pre-heating unit may further comprise a refrigerant pre-heating heat exchanger arranged between the cooling water heat exchanger and the refrigerant line connected to the suction section of the compressor, to indirectly transfer the heat recovered by the cooling water heat exchanger to the refrigerant line connected to the suction section of the compressor.

0027The cogeneration system may further comprise a refrigerant bypass line branched from the refrigerant line connected to the suction section of the compressor to allow the refrigerant in the refrigerant line to bypass the refrigerant pre-heating unit during a cooling operation of the cooling/heating unit.

0028The cogeneration system may further comprise a cooling water heat radiating unit arranged at the cooling water line to radiate the heat of the cooling water when it is unnecessary to supply heat to the suction side of the compressor.

0029In accordance with another aspect, the present invention provides a cogeneration system comprising: an engine, which drives a generator to generate electricity; a cooling/heating unit, which comprises at least one compressor, a four-way valve, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger, to establish a heat pump type refrigerant cycle; and an indoor heating unit to supply heat of exhaust gas discharged from the engine or heat of cooling water used to cool the engine to a heat exchanging zone of the indoor heat exchanger of the cooling/heating unit, and thus, to heat a confined space.

0030The cogeneration system of the present invention can achieve an enhancement in indoor heating efficiency because the cogeneration system includes the indoor heater to heat air blown to the indoor heat exchanger, using waste heat generated from an engine.

0031Since the indoor heater is arranged downstream from the indoor heat exchanger, the cogeneration system of the present invention also has an effect of preventing the refrigerant of the cooling/heating unit from being rapidly degraded.

0032In addition, the cogeneration system of the present invention achieves an improvement in heating performance because it is possible to pre-heat the refrigerant passing through the suction side of the compressor, using the waste heat generated from the engine, and thus, to increase the temperature of the temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

0033The above objects, and other features and advantages of the present invention will become more apparent after reading the following detailed description when taken in conjunction with the drawings, in which:

0034<figref idref="DRAWINGS">FIG. 1</figref> is a schematic configuration diagram illustrating a conventional cogeneration system;

0035<figref idref="DRAWINGS">FIG. 2</figref> is a schematic configuration diagram illustrating a cogeneration system according to an exemplary embodiment of the present invention;

0036<figref idref="DRAWINGS">FIG. 3</figref> is a schematic configuration diagram illustrating a cogeneration system according to another exemplary embodiment of the present invention in which a plurality of indoor heat exchangers are used; and

0037<figref idref="DRAWINGS">FIG. 4</figref> is a schematic configuration diagram illustrating a cogeneration system according to another exemplary embodiment of the present invention in which a plurality of cooling/heating units are used.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

0038Hereinafter, exemplary embodiments of a cogeneration system according to the present invention will be described with reference to the annexed drawings.

0039Although a number of embodiments may be implemented for the cogeneration system according to the present invention, the following description will be given in conjunction with the most preferable embodiment. Since the basic configuration of the cogeneration system is the same as that of the conventional cogeneration system, no detailed description thereof will be given.

0040<figref idref="DRAWINGS">FIG. 2</figref> is a schematic configuration diagram illustrating a cogeneration system according to an exemplary embodiment of the present invention.

0041As shown in <figref idref="DRAWINGS">FIG. 2</figref>, the cogeneration system includes an engine <b>50</b>, which operates, using fossil fuel such as natural gas or petroleum gas, a generator <b>52</b> to generate electricity, using a driving force of the engine <b>50</b>, an exhaust gas heat exchanger <b>72</b> to recover heat of exhaust gas of the engine <b>50</b>, a cooling water heat exchanger <b>82</b> to recover heat of cooling water of the engine <b>50</b>, and radiators <b>78</b> and <b>88</b> to radiate the exhaust gas heat and cooling water heat, respectively.

0042The cogeneration system also includes a cooling/heating unit <b>60</b>, which uses a heat pump type refrigerant cycle using waste heat generated from the engine <b>50</b>. The cooling/heating unit <b>60</b> includes at least one compressor <b>61</b>, a four-way valve <b>62</b>, an outdoor heat exchanger <b>63</b>, an expansion device <b>64</b>, an indoor heat exchanger <b>65</b>, and an indoor fan <b>66</b>, as in a general heat pump type cooling/heating unit, which can be used as both a cooling unit and a heating unit in accordance with reversal of a refrigerant flow in a refrigerant cycle of the cooling/heating unit.

0043In particular, an exhaust heat consuming heating unit <b>70</b> is connected to the cooling/heating unit <b>60</b>. The exhaust heat consuming heating unit <b>70</b> supplies the heat of the exhaust gas discharged from the engine <b>50</b> to a heat exchanging zone of the indoor heat exchanger <b>65</b>, and thus, to heat a confined space.

0044The exhaust gas heat exchanger <b>72</b> is included in the exhaust heat consuming heating unit <b>70</b>. The exhaust gas heat exchanger <b>72</b> is arranged at an exhaust conduit <b>54</b>, which discharges the exhaust gas of the engine <b>50</b>. In addition to the exhaust gas heat exchanger <b>72</b>, the exhaust heat consuming heating unit <b>70</b> includes an indoor heater <b>74</b> arranged at the heat exchanging zone of the indoor heat exchanger <b>65</b>, to perform heat exchange with indoor air, and a heating line <b>73</b>, which connects the exhaust gas heat exchanger <b>72</b> and indoor heater <b>74</b> to guide a heat transfer medium, for example, liquid, to flow between the exhaust gas heat exchanger <b>72</b> and the indoor heater <b>74</b>.

0045Preferably, the indoor heater <b>74</b> is configured such that the heat transfer medium, for example, liquid, which passes through the interior of the indoor heater <b>74</b>, performs heat exchange with air, which passes around the indoor heater <b>74</b>, as in a general air cooled type heat exchanger. The indoor heater <b>74</b> is arranged in parallel with the indoor heat exchanger <b>65</b> so that the indoor heater <b>74</b> performs heat exchange with indoor air in accordance with operation of an indoor fan <b>66</b>. The indoor heater <b>74</b> is arranged between the indoor heat exchanger <b>65</b> and the indoor fan <b>66</b>, downstream from the indoor heat exchanger <b>65</b> with respect to a flowing direction of indoor air.

0046The exhaust heat consuming heating unit <b>70</b> further includes an exhaust heat radiating unit <b>75</b> to radiate the heat recovered through the exhaust gas heat exchanger <b>72</b> to the atmosphere when it is necessary to prevent heat from being supplied to the indoor heater <b>74</b>, as in a cooling operation of the cooling/heating unit <b>60</b>. The exhaust heat radiating unit <b>75</b> includes a radiating line <b>77</b> branched from the heating line <b>73</b>, valves <b>76</b> respectively arranged at opposite ends of the radiating line <b>77</b>, and a radiator <b>78</b> arranged at the radiating line <b>77</b>.

0047Preferably, each valve <b>76</b> is a solenoid type three-way valve, which operates to change a fluid path between the heating line <b>73</b> and the radiating line <b>77</b> under the control of a control means included in the cogeneration system. The radiator <b>78</b> may be of an air cooled type such that the radiator <b>78</b> radiates heat to the atmosphere. Alternatively, the radiator <b>78</b> may take the form of a heat exchanger configured to heat water or to supply hot water.

0048In <figref idref="DRAWINGS">FIG. 2</figref>, reference character P designates pumps, each serving to force the heat transfer medium to flow through an associated line.

0049The cogeneration system according to this embodiment further includes a refrigerant pre-heating unit <b>80</b> to supply heat of the cooling water used to cool the engine <b>50</b> to a suction-side refrigerant line <b>67</b> of the compressor <b>61</b> in the cooling/heating unit <b>60</b>, and thus, to pre-heat a refrigerant passing through the refrigerant line <b>67</b>.

0050The refrigerant pre-heating unit <b>80</b> includes a cooling water line <b>81</b>, through which the cooling water of the engine <b>50</b> passes, and a cooling water heat exchanger <b>82</b> to recover cooling water heat from the cooling water line <b>81</b>, and to transfer the recovered heat to the refrigerant line <b>67</b> connected to a suction section of the compressor <b>61</b>.

0051A refrigerant pre-heating heat exchanger <b>84</b> is arranged between a heat exchanging line <b>63</b> connected to the cooling water heat exchanger <b>82</b> and a refrigerant line <b>67</b> connected to the suction section of the compressor <b>61</b>, to indirectly transfer the heat recovered by the cooling water heat exchanger <b>82</b> to the compressor suction-side refrigerant line <b>67</b>.

0052That is, the refrigerant pre-heating heat exchanger <b>84</b> is configured to achieve heat exchange between the heat exchanging line <b>83</b> connected to the cooling water heat exchanger <b>82</b> and the refrigerant line <b>67</b>.

0053A refrigerant bypass line <b>68</b> is branched from the refrigerant line <b>67</b> connected to the suction section of the compressor <b>61</b>. Valves <b>69</b> are arranged at opposite ends of the refrigerant bypass line <b>68</b> to change a refrigerant path between the refrigerant line <b>67</b> and the refrigerant bypass line <b>68</b>, respectively. The refrigerant bypass line <b>68</b> and valves <b>69</b> serve to cause the refrigerant passing through the refrigerant line <b>67</b> to bypass the refrigerant pre-heating unit <b>80</b> during the cooling operation of the cooling/heating unit <b>60</b>.

0054Preferably, each valve <b>69</b> has the same function as the valves <b>76</b> of the exhaust heat radiating unit <b>75</b>.

0055A cooling water heat radiating unit <b>85</b> is arranged at the cooling water line <b>81</b> to radiate the heat of the cooling water when it is unnecessary to supply heat to the suction side of the compressor <b>61</b>, as in the cooling operation of the cooling/heating unit <b>60</b>.

0056In order to radiate the heat of the cooling water to the atmosphere, the cooling water heat radiating unit <b>85</b> includes a radiating line <b>87</b> branched from the cooling water line <b>81</b>, valves <b>86</b> respectively arranged at opposite ends of the radiating line <b>87</b> to bypass the cooling water in the cooling water line <b>81</b> through the radiating line <b>87</b>, and a radiator <b>88</b> arranged at the radiating line <b>87</b>. The radiator <b>88</b> may be connected to other systems to use the waste heat of the cooling water, as in the above-described case in which the heat of the exhaust gas is used to heat water or to supply hot water.

0057Since the cogeneration system of this embodiment includes several heat exchangers including the exhaust gas heat exchanger <b>72</b>, cooling water heat exchanger <b>82</b>, refrigerant pre-heating heat exchanger <b>84</b>, and indoor heater <b>74</b>, it is possible to operate a water heater or other heat consumers even during a heating operation, by appropriately implementing a water-heating heat exchanger or a water-heating vessel having a heat exchanging function, which receive heat from the above heat exchangers, in accordance with the given design condition.

0058On the other hand, <figref idref="DRAWINGS">FIG. 3</figref> is a schematic configuration diagram illustrating a cogeneration system according to another exemplary embodiment of the present invention in which a plurality of indoor heat exchangers are used. In this case, a plurality of indoor heat exchangers <b>65</b>A, <b>65</b>B, and <b>65</b>C are arranged in serial or parallel in a single cooling/heating unit <b>60</b> to cool/heat a plurality of confined spaces, respectively. In this case, a plurality of indoor heaters <b>74</b>A, <b>74</b>B, and <b>74</b>C respective corresponding to the indoor heat exchangers <b>65</b>A, <b>65</b>B, and <b>65</b>C are included in an exhaust heat consuming heating unit <b>70</b>.

0059The indoor heaters <b>74</b>A, <b>74</b>B, and <b>74</b>C may have various arrangements, for example, a serial or parallel arrangement, on a heating line <b>73</b> in accordance with the given design condition. Also, the indoor heaters <b>74</b>A, <b>74</b>B, and <b>74</b>C may be selectively arranged only for a required one or ones of the indoor heat exchangers <b>74</b>A, <b>74</b>B, and <b>74</b>C.

0060It is also possible to use a plurality of compressors <b>61</b> and/or a plurality of outdoor heat exchangers <b>63</b>.

0061Constituent elements of the configuration of <figref idref="DRAWINGS">FIG. 3</figref> corresponding to those of <figref idref="DRAWINGS">FIG. 2</figref> are designated by the same reference numerals, respectively, and no description thereof will be given. Similarly, constituent elements of the configuration of <figref idref="DRAWINGS">FIG. 4</figref>, which will be described hereinafter, corresponding to those of <figref idref="DRAWINGS">FIG. 2</figref> are designated by the same reference numerals, respectively, and no description thereof will be given.

0062<figref idref="DRAWINGS">FIG. 4</figref> is a schematic configuration diagram illustrating a cogeneration system according to another exemplary embodiment of the present invention in which a plurality of cooling/heating units are used. In this case, distributors <b>90</b> and <b>95</b> are arranged at a heating line <b>73</b> connected to an exhaust heat consuming heating unit <b>70</b> and a refrigerant line <b>67</b> connected to a refrigerant pre-heating unit <b>80</b>, respectively, to distribute heat to a plurality of cooling/heating units <b>60</b>A, <b>60</b>B, and <b>60</b>C.

0063Alternatively, the distributors <b>90</b> and <b>95</b> may be arranged at the heat exchanging line <b>83</b> so that the distributors <b>90</b> and <b>95</b> are connected to the cooling/heating units <b>60</b>A, <b>60</b>B, and <b>60</b>C.

0064Meanwhile, the above-described heat exchangers may have various heat transfer configurations, for example, a heat transfer configuration in which heat transfer is carried out through a thermal conductor, or a heat transfer configuration in which heat transfer is carried out through a fluid present in a heat exchanger, in accordance with the given design condition or the given requirement.

0065Hereinafter, operation of the cogeneration system according to the present invention will be described.

0066During a heating operation of the cooling/heating unit <b>60</b>, a refrigerant flows through the compressor <b>61</b>, four-way valve <b>62</b>, indoor heat exchanger <b>65</b>, expansion device <b>64</b>, and outdoor heat exchanger <b>63</b>, in this order, to perform a heating operation.

0067Meanwhile, electricity, which is generated by a driving force from the engine <b>50</b>, may be used to operate the compressor <b>61</b>, indoor fan <b>66</b>, or outdoor fan <b>26</b>.

0068In particular, heat of exhaust gas discharged from the engine <b>50</b> during operation of the engine <b>50</b> is supplied to a confined space via the exhaust gas heat exchanger <b>72</b>, heating line <b>73</b>, and indoor heater <b>74</b>, thereby directly increasing the temperature of indoor air in the confined space, together with the indoor heat exchanger <b>65</b>. Thus, the performance of the cogeneration system to heat the confined space is enhanced.

0069Also, since the indoor heater <b>74</b> is arranged downstream from the indoor heat exchanger <b>65</b>, the indoor heater <b>74</b> does not perform direct heat exchange with the refrigerant passing through the indoor heat exchanger <b>65</b>. Accordingly, it is possible to prevent the refrigerant from being early degraded. In addition, since the indoor heater <b>74</b> is directly installed in the confined space such that the indoor heater <b>74</b> serves to directly increase the temperature of the confined space without using an additional heat exchanger, the heating performance of the cogeneration system is correspondingly enhanced.

0070Simultaneously with the above-described heating operation, heat of cooling water used to cool the engine <b>50</b> pre-heats the refrigerant passing through the suction side of the compressor <b>61</b> while passing through the cooling water heat exchanger <b>82</b> and refrigerant pre-heating heat exchanger <b>84</b>. Accordingly, the temperature of the refrigerant emerging from the compressor <b>61</b> is increased, so that the refrigerant emits heat of a higher temperature while passing through the indoor heat exchanger <b>65</b>, which serves as an evaporator. Thus, an enhancement in the heating efficiency of the cogeneration system is achieved.

0071Since the refrigerant line <b>67</b> is indirectly connected to the cooling water heat exchanger <b>82</b> such that the refrigerant line <b>67</b> performs heat exchange with the cooling water heat exchanger <b>82</b> via the refrigerant pre-heating heat exchanger <b>84</b>, it is possible to prevent the refrigerant from being over-heated, and thus, rapidly degraded.

0072Although the cogeneration system of the present invention has been described as using both the heat of exhaust gas and the heat of cooling water through the exhaust heat consuming heating unit <b>70</b> and the refrigerant pre-heating unit <b>80</b>, it may be possible to perform a heating operation, using a selected one of the heat sources, if necessary.

0073When the cooling/heating unit <b>60</b> operates in a cooling mode or stops the cooling/heating operation thereof, it is necessary to prevent heat of exhaust gas and heat of cooling water generated from the engine <b>50</b> from being supplied to the cooling/heating unit <b>60</b>. In this case, accordingly, the valves <b>69</b> of the refrigerant line <b>67</b> and the valves <b>76</b> of the exhaust heat consuming heating unit <b>70</b> are operated to change fluid paths associated with the exhaust gas heat and cooling water heat, respectively.

0074As a result, the refrigerant in the cooling/heating unit <b>60</b> flows through the bypass line <b>68</b>, and the exhaust gas heat exchanging fluid and cooling water flow through the radiating lines <b>77</b> and <b>87</b>, respectively. Thus, the exhaust gas heat and cooling water heat are discharged to the atmosphere or transferred to other waste heat consuming systems, respectively.

0075As apparent from the above description, the cogeneration system of the present invention can achieve an enhancement in indoor heating efficiency because the cogeneration system includes the indoor heater to heat air blown to the indoor heat exchanger, using waste heat generated from an engine.

0076Since the indoor heater is arranged downstream from the indoor heat exchanger, the cogeneration system of the present invention also has an effect of preventing the refrigerant of the cooling/heating unit from being rapidly degraded.

0077In addition, the cogeneration system of the present invention achieves an improvement in heating performance because it is possible to pre-heat the refrigerant passing through the suction side of the compressor, using the waste heat generated from the engine, and thus, to increase the temperature of the temperature.

0078Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.